A pair of interlocking nautilus gears. More...

#include <NautilusGear.h>

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Public Member Functions
	CNautilusGear ()
	Constructor.

	~CNautilusGear ()
	Destructor.

void	Move ()
	Move gears in synchrony.

void	Action ()
	Reverse gears.

Public Member Functions inherited from CLevel
	CLevel (eSprite)

virtual	~CLevel ()
	Default constructor.

virtual void	Draw ()
	Draw objects in level.

Private Member Functions
b2Body *	CreateBase (float, float)
	Create invisible base.

b2Body *	CreateGear (float, float, eSprite, b2BodyType)
	Create gear.

Private Attributes
b2RevoluteJoint *	m_pJoint = nullptr
	Ptr to left gear revolute joint.

const float	a = 98.0f
	Maximum radius in Render World units, from image.

const float	b = 34.0f
	Minimum radius in Render World units, from image.

const float	d = 0.5f*logf(a/b)/b2_pi
	Denominator for computing orientation.

Additional Inherited Members
Protected Member Functions inherited from CLevel
CLineObject *	CreateLine (b2Body , const b2Vec2 &, bool, b2Body , const b2Vec2 &, bool)
	Create new line object.

Protected Attributes inherited from CLevel
std::vector< CObject * >	m_stdObject
	Object pointers.

std::vector< CLineObject * >	m_stdLine
	Line list.

eSprite	m_eBgSprite
	Type of background sprite.

Static Protected Attributes inherited from CCommon
static b2World *	m_pPhysicsWorld = nullptr
	Pointer to Box2D Physics World.

static CBox2DRenderer *	m_pRenderer = nullptr
	Pointer to the renderer.

static CLevel *	m_pLevel = nullptr
	Pointer to current level.

static eLevel	m_eCurLevel = eLevel::Windmill
	Current level.

static eDrawMode	m_eDrawMode = eDrawMode::Sprites
	Draw mode.

Detailed Description

A nautilus gear is a gear in the shape of a nautilus shell. This level will animate a pair of nautilus gears. The left gear has a revolute joint with a motor. The right gear has variable speed, so it cannot be animated by Box2D. We have to animate it ourselves which means doing a little math.

Constructor & Destructor Documentation

◆ CNautilusGear()

CNautilusGear::CNautilusGear ( )

Create gear wheel objects and physics bodies, with a revolute joint between the left gear and the background. Store a pointer to the revolute joint in m_pJoint so that the motor speed and direction can be changed.

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◆ ~CNautilusGear()

CNautilusGear::~CNautilusGear ( )

Null destructor.

Member Function Documentation

◆ Action()

void CNautilusGear::Action ( )

virtual

Reverse the gears by setting the motor speed on the revolute joint for the left gear. Assumes that m_pJoint contains a pointer to the revolute joint.

Reimplemented from CLevel.

◆ CreateBase()

b2Body * CNautilusGear::CreateBase	(	float	x,
		float	y )

private

Create an invisible base object and phsyics body to attach the largest gear wheel to. The base has no sprite and no shape in Physics World. The latter means it doesn't collide with anything.

Parameters

x	X coordinate in Physics World units.
y	Y coordinate in Physics World units.

Returns: Pointer to the cog wheel body in Physics World.

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◆ CreateGear()

b2Body * CNautilusGear::CreateGear	(	float	x,
		float	y,
		eSprite	t,
		b2BodyType	bt )

private

Create the object and physics body for a gear wheel.

Parameters

x	X coordinate in Physics World units.
y	Y coordinate in Physics World units.
t	Sprite type of the gear wheel.
bt	Box2D body type.

Returns: Pointer to the gear body in Physics World.

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◆ Move()

void CNautilusGear::Move ( )

virtual

Make the right gear rotate in synchrony with the left gear. Assumes that the left gear was created first.